This application claims the priority benefit of Japanese application serial no. 2001-223585 filed on Jul. 24, 2001, 2001-223586 filed on Jul. 24, 2001, 2001-223587 filed on Jul. 24, 2001, 2001-223588 filed on Jul. 24, 2001, 2001-223589 filed on Jul. 24, 2001 and 2001-223590, filed on Jul. 24, 2001.
1. Field of the Invention
This invention relates to a Stirling refrigerator.
2. Description of Related Art
In recent years, a Stirling refrigerator has been suggested as a refrigerating device using a substitute for environmentally problematic Freon, or as a refrigerator whose operation temperature is in a broader range than that of a conventional cooling device. This refrigerator can be applied to the apparatuses utilizing cooling heat for business or household use as a freezer, a refrigerator, and a throw-in type cooler, and the cooling heat utilizing apparatuses of all industrial fields such as a low-temperature fluid circulator, a low-temperature isothermal unit, an isothermal tank, a heat shock test device, a freezing drier, a thermal property test device, a blood/cell storage-devices, a cold cooler, and other various cooling heat devices. Furthermore, this refrigerator is compact, high in coefficient of performance, and excellent in energy efficiency.
In a heat engine of the Stirling refrigerator, working gas is sealed into a housing of the machine in a sealed condition, wherein the housing forms the body of the machine, and has a crank chamber and a motor chamber. The working gas flows through a flow passage between a compression chamber (high-temperature chamber) and an expansion chamber (low-temperature chamber). A radiating heat exchanger (at high-temperature side), a regenerator and a cooling heat exchange (at low-temperature side) are disposed along the flow passage of the working gas. A cooling heat refrigerant and a radiating refrigerant are respectively heat-exchanged by the radiating and cooling heat exchangers, and a heat exchanging performance is enhanced by radiating and absorbing of heat.
The working gas is expended or compressed by expansion or compression piston through driving devices such as connecting rods that are disposed on a crank shaft driven by a motor. A shock-resistant balancer is disposed on the crank shaft.
A coupler for injecting the working gas is set in a crank chamber and a buffer chamber (a back space of the piston inside the compression or the expansion cylinder) of a Stirling refrigerator such as Stirling heat engine. The coupler can link the source of the working gas in order to inject the working gas.
A pressure sensor, which also functions as a pressure adjuster, is detachably installed on an installing block through a pressure sensor fitment (referring to the prior art example in FIG. 7B).
The Stirling refrigerator has a problem, which is so-called oil rising, that oil or oil mist rises from a crank chamber along the piston rods. Regarding the oil rising, as the oil or oil mist enters the cylinders, the oil or oil mist adheres to the inner surfaces of the cylinder effecting the sealing performance of the piston rings. Not only the durability and the reliability of the refrigerator are obviously decreased, but also the compressed gas and oil enter the compression gas utilizing apparatuses, so that the compression gas utilizing apparatuses or parts treated by compression gas utilizing apparatuses is deteriorated.
For solving the oil rising problem, the conventional piston rod is sealed by an oil ring seal. The oil ring seals are generally made of gum and have been developed using various structures and materials, but they are not necessarily sufficient in sealing performance or durability.
Therefore, inventors have proposed an oil seal bellows (referring to Japanese Patent application 10-365371) as a rod seal (piston rod seal) of a Stirling refrigerator. In the invention of 10-365371, an oil seal metal bellows is set between a housing of the Stirling refrigerator and the compression and expansion cylinders, preventing the oil rising from entering the compression cylinder and the expansion cylinder from the crank chamber along the surface of the piston rods.
The balancer installed on the crank shaft is generally fixed by screws onto an installing surface formed on the crank shaft (a flat surface mostly). However, the balancer moves (rotates) centered on the screws with respect to the crank shaft during operation and therefore the installing portion drifts, so that the shock-resistant performance is reduced.
Although the coupler for injecting working gas is separated from the Stirling refrigerator, it is still affected by the vibration due to the operation of the Stirling refrigerator, so that the fixing screws of the coupler loosen and thus the working gas leaks.
In the Stirling refrigerator, the oil seals are used to seal the cylinders (compression, and expansion cylinders) in order to prevent the oil from entering the cylinder along the piston rod from the crank chamber during operation. However, as the pressure difference of working gas between the crank chamber and cylinders is created, problems of oil seals being imperfect or broken occur.
It is needed to regularly check the working gas pressure in the crank chamber to inject the working gas through the coupler, to adjust flare nuts attached to the pressure sensor, or to adjust the working gas pressure. However, because the flare nuts are buried inside the pressure sensor fitment and are not easy to approach (referring to prior art in FIG. 7B), it is not easy to adjust working gas during the maintenance, such as the regular check of the fix etc.
Inventors developed the above oil seal bellows installed in the Stirling refrigerator to further increase the life time of the oil seal bellows. However, this has become not preferable due to fatigue generated when they repeat moving back and forth in a predetermined stroke in a compression and a expansion directions.
The regenerator is generally formed by filling with tiny wire-netting material. The inferior quality of the wire-netting material, which turns bad when time goes by, will be cut into pieces and flow with working gas into the heat exchangers, high-temperature chamber, low-temperature chamber, etc., so that the flowing resistance of working gas increases and the smooth activity of the piston is frustrated, causing the performance to be deteriorated and damaged.
The space of the cylinders forming the high-temperature chamber or the low-temperature chamber and the space between housings are sealed by the rod seals, such as the oil seal bellows, so that the oil doesn""t flow from the crank chamber of the housing into the space of the cylinders. However, if a pressure difference of working gas exists between the space of cylinders and inside of the housing, it burdens the rod seal, makes the performance decrease and causes breaking. The pressure in the space of the cylinders is not stable, the performance of the heat engine is therefore not stable.
Because the housing is generally formed by casting and the working gas filled into the housing has a small molecular weight, such as helium or the like, it should be noted that the gas leaks from the thin part of the casting.
Especially, when some accessories, such as terminal box are fixed to the thin part of the housing by screws, the thickness is relatively thin in the region of screw hole so that the working gas leaks form the relatively thin part to the outside. The working gas pressure inside the housing therefore decreases, and the performance, the durability of the rod seal and performance of heat engine worsens.
According to the foregoing description, an object of this invention is to provide a Stirling refrigerator preventing the installing position moving with respect to the crank shaft, and the balancer can be fixed onto the crank shaft without moving in order to improve the shock-resistant function.
Another object of the prevent invention is to provide a balancer, which prevents looseness of the fixing screws of the coupler, in order to prevent the working gas leak.
Still another object of the prevent invention is to provide a pressure sensor installing fitment and an installing structure such that the working gas in the crank chamber can be easily adjusted without taking off some special part such as a flare nut for adjusting pressure in the pressure sensor.
Still another object of the prevent invention is to provide an oil seal bellows to prevent the oil rising with higher sealing performance and longer life in order to improve the performance, reliability and durability of the machine.
Still another object of the prevent invention is to provide a Stirling refrigerator even if the wire-netting material is cut into pieces, they don""t flow with working gas from the regenerator, so the trouble caused by the cut pieces can be prevented, the performance of the machine can be kept from deteriorating, and the device damage can be prevented.
Still another object of the present invention is to provide a fixing structure to solve the problem of sealing working gas into a Stirling heat engine by fixing a fitting onto the thin part of the housing with screws, so the working gas leak from the thin part in the screw hole region can be prevented.
According to the objects mentioned above, there is provided a Stirling refrigerator, comprising: a housing formed by casting, wherein a motor and a crank are disposed inside the housing, and a working gas is sealed inside the housing, a part of the housing has a thin portion, and a fitting is installed on the thin portion, and the fitting is fixed on the thin portion by a tapping screw; a cylinder fixed on a top of the housing; a piston, reciprocating inside the cylinder; a piston rod moving with the crank, wherein one end of the piston rod links the piston and passes through the housing; and an oil seal bellows sealing a space between the housing and the cylinder, wherein a tip end of the oil seal bellows is sealed and fixed on the piston or the piston rod inside the cylinder, and a base end of the oil seal bellows is installed on the housing, and the oil seal bellows reciprocating with a stroke, wherein the tip end of the oil seal bellows is compressed to a compression side from a position of free length then returns to the position of free length.
Additionally, the oil seal bellows is applied in the compression cylinder and in the expansion cylinder or one of them.
Moreover, the fitting is a terminal box.
Furthermore, the working gas is helium, hydrogen or argon.
Furthermore, there is provided a Stirling refrigerator, further comprising an balancer installing structure, wherein the crank having a crank shaft driven by the motor, and the balancer installing structure is fixed on the crank shaft by a screw, and on each surface of the crank shaft and the balancer, which contacts with each other, has a small hole acentric from the screw, and a position determining pin is used to insert in the small hole in order to prevent the balancer from moving onto an installing face of the crank shaft.
Additionally, each amount of the small holes formed on each of the surfaces and the position determining pin is one or two or more.
Moreover, the position determining pin is a split pin.
Furthermore, there is provided a Stirling refrigerator, further comprising a working gas injecting coupler installing structure in order to connect to a working gas supply pipe coming from a working gas source and to inject the working gas into the Stirling refrigerator, and the working gas injecting coupler installing structure comprising: a fixing screw, fixing and connecting the coupler and the working gas supply pipe; a coupler installing fitment; and a coupler shock-resistant fitment fixed on the coupler installing fitment with the coupler.
Additionally, the coupler shock-resistant fitment is fixed on the coupler installing fitment, and the coupler shock-resistant fitment contacts with the fixing screws in a way that the fixing screws won""t be loosened.
Moreover, the Stirling refrigerator further comprising a crank chamber or a buffer chamber, wherein the coupler for injecting the working gas injects the working gas into the crank chamber or the buffer chamber.
Furthermore, the shock-resistant fitment has a door-shaped flange.
Additionally, the shock-resistant fitment is a pair of members, wherein each of the members is L-shaped sectional.
Furthermore, there is provided a Stirling refrigerator further comprising a crank chamber, a installing block and a pressure sensor installing structure, wherein the installing block has a through hole connecting the crank chamber, and a pipe for supplying the working gas connects the through hole of the installing block, and a pressure sensor, which is pressure-adjustable, is installed on the installing block through fixing a pressure sensor installing fitment having a slit, and a pressure of the pressure sensor is adjusted by inserting an adjusting instrument from the slit.
Additionally, the pressure sensor installing fitment is C-shaped planar.
Furthermore, there is provided a Stirling refrigerator further comprising a high-temperature chamber and a radiating heat exchanger, a low-temperature chamber and a cooling heat exchanger, a working gas flow passage and a regenerator, wherein the working gas flow passage is between the high-temperature chamber and the low-temperature, and the regenerator is disposed between the radiating heat exchanger and the cooling heat exchanger, and an exit and an entrance of the working gas are formed respectively at two ends of the regenerator, and filters are respectively disposed on the exit and the entrance.
Additionally, the regenerator is made of tiny wire-netting material.
Moreover, the filters are made of porous sinter material or ceramic.